Antenna structure



H. JASIK ANTENNA STRUCTURE July 12, 1960 2 Sheets-Sheet 1 Original Filed March 7, 1949 :FIEE

INVENTOR. By IZ/EHIZ/ Jaszk ANTENNA STRUCTURE Henry Jasik, Flushing, N.Y., assignor to Andrew Alford, Boston, Mass.

Original application Mar. 7, 1949, Ser. No. 79,969. Di-

vided and this application Mar. 5, 1954, Ser. No.

9 Claims. (Cl. 343-807) The present invention is a division of my copending patent application, Serial No. 79,969, filed March 7, 1949, now Patent No. 2,700,112.

The need for a high frequency dipole of a simple design, having substantially unchanging characteristics over a Wide frequency band has existed for some time. The

chief objection to antennas of this general type is thatweak when subjected to tension. In previous designs in-- sulators as used are often subjected to tensile stress, with the result that they are frequently fractured thus render- I ing the antenna useless.

In my invention, two radiating outer sleeves are employed with an insulating spacer separating the sleeves. The end of one of the outer sleeves spaced away from the other end near the insulating collar is at zero potential. A metallic means for spanning the sleeves in their longitudinal direction exerts a compressional stress be tween opposite faces of the insulating collar.

The structure of the present invention may be carried out in various forms as for instance, in a completely balanced structure in which a gap exists on either side of the neutral plane or in a unit where the neutral plane is at one end of the structure. The structure may also employ special coupling means connected between coaxial feed cables and the antenna or other special compensating elements which enter individually and in combination to form the distinguishing features of the present invention.

Without further discussing the merits and advantages of the present invention which will be more fully learned from the specifications and claims set forth below, the invention in its various embodiments will be described in connection with the drawings forming a part of the specification in which:

Figure l is a longitudinal section taken through one form of the antenna. 7

' Figure 2 shows a substantially equivalent electrical circuit diagram for the structures of Figure 1.

Figure 3 shows in longitudinal section a modified form of the structure shown in Figure 1.

Figure 4 shows a substantially equivalent bilineal circuit diagram for the structure of Figure 3.

Figure 5 shows a longitudinal section of a further modification of the structure shown in Figure l, and,

Figure 6 shows a substantially equivalent electrical circuit diagram of the structure shown in Figure 5.

In'the embodiment of my invention shown in Figure 1, 1 and 2 are sleeve radiating elements of metallic material, the lower part of 2 being electrically connected to a ground plate or base 21 by welding or by other suitable ICE- means while the upper sleeve 1 is capped by a cover 22 which may be of metal. The base 21 may be considered to be at zero potential. The member 3 is an insulating,

collar which may be made of a tough plastic material and having a shape to fit snugly against the outer surface of the sleeve ends with a centrally inwardly extending flange filling the space between the end edges of the sleeves separating the two sleeves 1 and 2 by a desired gap distance. The element 4 is a metallic rod which at one end is secured by welding or by other suitable means to the ground plate 21, making electrical connection and at the other end is threaded as at 24 to receive a washer and nut 25 which is tightened against a conductive plate 26 fitting inside the tube 1 and welded to its inner wall just beyond the end resting on the insulator 3 so that the adjacent ends of the tubes 1 and 2 are pressed against opposite faces respectively of the insulator flange putting the insulator under substantial initial compression. The element 5 is a coaxial cable with an inner conductor 6 and an outer conductor 7 which is conductively connected tosleeve 2. The coaxial cable 5 passes through the plate 21 and is connected to the high frequency line by means of the cable connector 20 which may be silver soldered to the plate 21. The inner conductor 6 of cable 5 is connected to rod 4 by the connector 13. The rod 4 is connected to plate 26 and hence a potential is set up across the gap separating sleeves 1 and 2. If desired, the plate 26 may be closer to the insulator flange than shown in Figure l, in which case the series inductance 12 (Figure 2), on one side of the coaxial line would be decreased. The potential which is impressed by the connections of the-coaxial cable sets up radiating currents on the outer surfaces of sleeves 1 and 2. The coaxial cable 5 with inner conductors6 and outer conductor 7, apply a voltage to a shunt reactance formed by the reentrant circuit consisting of outer and inner surfaces of the tube 18, the lower part of rod 4, the inner surface of plate 21, and of the tube 2. The tube 18 has a metallic plug 14 at its upper end through which the rod 4 is threadedly engaged with a washer 27 and nut 28 to clamp tightly the eyelet end of the conductor 13 and the rod 4 to the top surface of the plug. The elfect of this reactance is shown as a shunt 13' (Figure 2) across the coaxial cable. This reactance is used to help compensate the impedance as seen by the coaxial line.

The radiation impedance 10 (Figure 2) of the antenna proper can be changed by varying the diameter and length of sleeves 1 and 2. Two other variations as noted just below are useful for impedance compensation. The length of the insulating collar 3 is used to control the shunt capacitive reactance across the radiation impedance. A decrease in the gap space will decrease the capacitive reactance. The upper part of rod 4, namely the section 29 together with the plate 26 and the small section of the sleeve 1 to the gap form the series inductance in one conducting element of the coaxial cable which is designated as 12 in Figure 2, as has been stated.

The complete equivalent compensation network, as has been stated, is shown in Figure 2, the elements of which have already been referred to above. In part recapitulation 10 is the radiation impedance of the sleeves 1 and 2, -11 is the capacitive reactance due to the gap spacing, 12 is in the inductive reactance of the upper part of rod 4, and 13 is the reactance as explained above across the coaxial line.

Another embodiment of my invention is shown in Figure 3. The same elements used in the modification of Figure 1 will bear the same numerals in all of the other figures where there is no structural change. In Figure 3, the rod 4 extends through the cap 22' and compresses the sleeves 1 and2 together against the insulator Patented July 12, 1960;

j. l 2,945,232 V w 3 from their extremeends by tightening the nut on the rod-4 on the outside'of the'cap 22. The internal plate is thereforeomitted and theicoaxial cable 5 has its internal conductor 6 connected by a short lead 3d to the end of the tube l-adjacent the gap. The outer conductor 7-is 'in good-electrical-oontact with the inside of'the'tube 2 substantially-up to the end adjacent the gap.

The equivalent circuit diagram is shown in Figure 4. The gap reactance is shunted across the coaxial cable as indicated at 11 :with a radiation impedance 1% also in shunt across the coaxial cable. Due to the shortness of thezconnector 30, there issubstantially no series reactance on one side ofthe line as-indicated in Figure 2, but there is a considerable shunt inductive reactance made up of the rod 4',,part of the base 21, and part of the upper sleeve 1. The lowerseotion of the rod 4 and base 21 corresponds to a reactance 32 which is substantially equivalent to reactance '13 of Figure 2, while the reactance $1 accounts for the additional upper section of the" rod 4'.

The arrangement shown in Figure 5 is a balanced system consisting-of a structure which electrically difiers somewhat "from the structure of the other figure. In Figure 5 the structure-on the-left is the same as that on the right with a neutralmid-plane.-

- Thedevicecomprisesinner sleeves 41, actually a single tube and outer sleeves '42, spaced by the insulators 43 which correspond-to similar elements described in connection with the other modifications. concentrically positioned and supported within the sleeves and insulators, are the feeder tubes 44 Within which is positioned the tie rod 4-5 which extends from one extreme outer sleeve 42 to the other and serves as the means for putting the sleeves and insulators under compression. For this purpose plates 46 are secured inside the sleeves 42 near their outer ends by welding the sleeves to those plates while the rod 45 extends through holes in the center of the plates and on the other side isdrawn tightly by a suitable nut 47. Within the sleeves 42- are plates 48 through which. the feeders 44 extend, which feeders are concentrically positioned with respect to the sleeves. These plates48 are also welded to the tubes or sleeves 42 and make good electrical connections both with the inside ofwthe sleeves 42 and theoutside of the feeder 44. The position of the plates 48 with respect to the gap has a substantial eifect on the value of the terminal impedance of the concentriefeeders consisting of the tubes 44 and 41. An increase in-this spacing has the effect of increasingthe' inductivereactance in series with impedance of the end part of sleeve 4-2. The two plates 46 and 48 provi-destrongsupports for the tube 44.

The outer ends of the: sleeves 42 may be capped by caps 49 which may be secured inany desirable way. Insulatingdiscs 50 act as supports for the tie rod 45 and spacers for the tierod within the tube 44.

'The single tube 41 has an opening at the top center sectionclosediby acover plate 51 fitting on a cover plate mounting. 52 so that the device can be reached in the region where the feed lines are brought up to the structure' just described. 7

The means'and method of feeding the sleeve antenna is-=optionaland maybe accomplished by the application o'fa balanced feed, compensated as desired, between right and'left' feeders 44-. In Figure 5 there is shown a single coaxial cable-5'3 with an outer conductor 54 connected by a connector 55 tothe feeder 44 and an inner conductor 56- connected-by a connector 57 to the other feeder 44'. A section of a compensating reactance 58 is also shown connected to the connector 57. The balanced voltage in this case is supplied between the outer conduotor-54- 'and the connector 57 or the-tube 58.

The-equivalent circuit diagram is shown in Figure 6. The balanced supply voltage isshown at 5-9. This is applied to a'transmission line 60 consisting of the sleeve or'tube' 44 asthe high side and the inner side ot'the sleeve 4-1 as the grounded side. Reactance 64 comprises the inside of the tube-44 and the plate'46 to-the-tie rod 45 and the tie rod 45 to the neutral plane. 61 represents a series inductance which includes the plates 48 and the section of the tube 42 from where the plate 48 is connected to it, to the gap. 68 represents the gap shunted across the line and 63 represents the radiation impedance. It will be understood that the circuit is only a half circuit of Figure 5 since the same elements in-the same position are repeated for each side.

In all of the circuits shown, the system has a neutral or ground plane away from the air gap and this distinguishes this type-of antenna from the so called dipole antenna. In the balanced system of the present invention, the antenna length may correspond to a half wave length of a frequency chosen in the band width. In the unbalanced system it may correpsond to a quarter of a wave length and is fed in the manner indicated above. p

Having now described my invention, I claim:

1. A broad band non resonant antenna system comprising two radiating sleeves, means providing a low impedance gap between said sleeves including an insulating collar positioned between adjacent edges of the sleeves and against which saidedges rest, a metallic tie'rod extending into the sleeves, conductive supporting means secured Within each sleeve to support said tie rod for compressing the sleeves against said collar in a longitudinal direction and means contained within the sleeve for feeding the sleeves at a point closely across said collar with one of the other ends of the sleeves maintained at a neutral potential. V

2. A broad band 'non resonant antenna system comprising two radiating sleeves coaxially positioned, means providing a low impedance gap between said sleeves including an insulating. collar spacing adjacent edges of the sleeves from each other, metallic tie rod means positioned on the inside of each sleeve and exerting a compression on the sleeves across the collar, a coaxial cable extending into one of the sleeves from one end and having one conductor secured to one sleeve near the collar and the other conductor connected to theother sleeve on its inside just across the insulator and means maintaining the outer end of one of said sleeves at ground potential.

3. A broad band non resonant antenna system comprising two radiating sleeves, means providing a low impedance gap between said sleeves including an insulating collar positioned between. adjacent edges of the sleeves and against which said edges rest, conductive supporting bracket elements secured to the inside of each sleeve, a metallic 'tie rod extending into'the sleeves longitudinally to compress said collar and means contained within the sleeves for feeding the sleeves at points just across said collar with one of the other endsof the sleeves maintained at a neutral potential.

4. A broad band non resonant antenna system comprising two radiating sleeves, means providing a low impedance gap between said sleeves including an insulating collar positioned between adjacent edges of the sleeves and against. which said edges rest, means capping said sleeves at their extremities away from said adjacent edges, a tie rod extending through said sleeves engaging said caps to exert pressure against the collar by the sleeves from each inner edge, and means comprising an inner and outer conductor for feeding the sleeves at points across said collar with one extremity of one sleeve maintained at a neutral potential.

5. A bro-ad band non resonant antenna comprising two radiating sleeves, an insulating-collarpositioned between adjacent edges of the sleeves andagainst which said edges rest, a conductive member bridging. across one of'said sleeves on. theinside' close to the insulating collar, a second conductive bridging member within the other sleeve at its end opposite said adjacent edge, a

metallic tie rod member joined to each of said bridging members and exerting a compressional force Within the sleeves across the insulator, means for feeding said sleeves across said insulators and means for maintaining said other sleeve at said end opposite said adjacent edge at ground potential.

6. A broad band non resonant antenna comprising two radiating sleeves, an insulating collar positioned between adjacent edges of the sleeves and against which said edges rest, a conductive member bridging across one of said sleeves on the inside close to the insulating collar, a second conductive bridging member within the other sleeve at its end opposite said adjacent edge a metallic tie rod member joined to each of said bridging members and exerting a compressional force with the sleeves across the insulator, a coaxial cable extending within said other sleeve from said end opposite said adjacent edge to the vicinity of the insulating collar and having its outer conductor connected to the inside of said other sleeve and its inner conductor connected to said tie rod in the vicinity of said insulator and means for maintaining the said other sleeve at said end opposite said adjacent edge at ground potential.

7. An antenna as described in claim 6, in which the tie rod below the point of connection of said inner con doctor has a conductive sleeve electrically connected to it.

8. An antenna as described in claim 4, in which the feeding means comprises a coaxial cable attached to the inside wall of one sleeve and having its outer conductor electrically connected to said wall on the inner surface near to the end adjacent the insulator and its inner conductor extending across the gap formed by the insulator tod the adjacent end of the other sleeve on the inner 51 e.

9. A broad band non resonant antenna system comprising two radiating sleeves, means providing a gap between said sleeves including an insulating collar positioned between adjacent edges of the sleeves and against which said edges rest, means capping said sleeves at their extremities away from said adjacent edges, a tie rod extending through at least one o f said sleeves with its ends terminating near and engaging ends of said sleeves thereby exerting compressional force upon said sleeves, and with at least one end of said rod engaging one of said capping means, and means comprising an inner and outer conductor for feeding the sleeves at points across said collar with one extremity of one of said sleeves maintained at neutral potential.

References Cited in the file of this patent 

